Block family-based error avoidance for memory devices

ABSTRACT

An example memory sub-system includes a memory device and a processing device, operatively coupled to the memory device. The processing device is configured to initialize a block family associated with a memory device; initialize a timeout associated with the block family; initializing a low temperature and a high temperature using a reference temperature at the memory device; responsive to programming a block residing on the memory device, associate the block with the block family; and responsive to at least one of: detecting expiration of the timeout or determining that a difference between the high temperature and the low temperature is greater than or equal to a specified threshold temperature value, close the block family.

REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/950,341, filed Dec. 19, 2019, the entirety of whichis incorporated herein by reference.

TECHNICAL FIELD

Embodiments of the disclosure are generally related to memorysub-systems, and more specifically, are related to block family-basederror avoidance for memory devices.

BACKGROUND

A memory sub-system can include one or more memory devices that storedata. The memory devices can be, for example, non-volatile memorydevices and volatile memory devices. In general, a host system canutilize a memory sub-system to store data at the memory devices and toretrieve data from the memory devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be understood more fully from the detaileddescription given below and from the accompanying drawings of someembodiments of the disclosure.

FIG. 1 illustrates an example computing system that includes a memorysub-system in accordance with some embodiments of the presentdisclosure.

FIG. 2 schematically illustrates the temporal voltage shift caused bythe slow charge loss exhibited by triple-level memory cells, inaccordance with some embodiments of the present disclosure.

FIG. 3 depicts an example graph illustrating the dependency of thethreshold voltage offset on the time after program (i.e., the period oftime elapsed since the block had been programmed, in accordance withsome embodiments of the present disclosure.

FIG. 4 schematically illustrates a set of predefined threshold voltageoffset bins, in accordance with embodiments of the present disclosure.

FIG. 5 schematically illustrates block family management operationsimplemented by the block family manager component of thememory-sub-system controller operating in accordance with embodiments ofthe present disclosure.

FIG. 6 schematically illustrates selecting block families forcalibration, in accordance with embodiments of the present disclosure.

FIG. 7 schematically illustrates example metadata maintained by thememory sub-system controller for associating blocks and/or partitionswith block families, in accordance with embodiments of the presentdisclosure.

FIG. 8 is a flow diagram of an example method 800 of block familymanagement implemented by a memory sub-system controller operating inaccordance with some embodiments of the present disclosure.

FIG. 9 is a flow diagram of an example method 800 of performing a readoperation by a memory sub-system controller operating in accordance withsome embodiments of the present disclosure.

FIG. 10 is a block diagram of an example computer system in whichembodiments of the present disclosure can operate.

DETAILED DESCRIPTION

Embodiments of the present disclosure are directed to block family-basederror avoidance for memory devices. A memory sub-system can be a storagedevice, a memory module, or a hybrid of a storage device and memorymodule. Examples of storage devices and memory modules are describedbelow in conjunction with FIG. 1. In general, a host system can utilizea memory sub-system that includes one or more components, such as memorydevices that store data. The host system can provide data to be storedat the memory sub-system and can request data to be retrieved from thememory sub-system.

A memory sub-system can utilize one or more memory devices, includingany combination of the different types of non-volatile memory devicesand/or volatile memory devices, to store the data provided by the hostsystem. In some embodiments, non-volatile memory devices can be providedby negative-and (NAND) type flash memory devices. Other examples ofnon-volatile memory devices are described below in conjunction withFIG. 1. A non-volatile memory device is a package of one or more dice.Each die can consist of one or more planes. Planes can be groups intologic units (LUN). For some types of non-volatile memory devices (e.g.,NAND devices), each plane consists of a set of physical blocks. Eachblock consists of a set of pages. Each page consists of a set of memorycells (“cells”). A cell is an electronic circuit that storesinformation.

Data operations can be performed by the memory sub-system. The dataoperations can be host-initiated operations. For example, the hostsystem can initiate a data operation (e.g., write, read, erase, etc.) ona memory sub-system. The host system can send access requests (e.g.,write command, read command) to the memory sub-system, such as to storedata on a memory device at the memory sub-system and to read data fromthe memory device on the memory sub-system. The data to be read orwritten, as specified by a host request, is hereinafter referred to as“host data”. A host request can include logical address information(e.g., logical block address (LBA), namespace) for the host data, whichis the location the host system associates with the host data. Thelogical address information (e.g., LBA, namespace) can be part ofmetadata for the host data. Metadata can also include error handlingdata (e.g., ECC codeword, parity code), data version (e.g. used todistinguish age of data written), valid bitmap (which LBAs or logicaltransfer units contain valid data), etc.

A memory device includes multiple memory cells, each of which can store,depending on the memory cell type, one or more bits of information. Amemory cell can be programmed (written to) by applying a certain voltageto the memory cell, which results in an electric charge being held bythe memory cell, thus allowing modulation of the voltage distributionsproduced by the memory cell. Moreover, precisely controlling the amountof the electric charge stored by the memory cell allows to establishmultiple threshold voltage levels corresponding to different logicallevels, thus effectively allowing a single memory cell to store multiplebits of information: a memory cell operated with 2^(n) differentthreshold voltage levels is capable of storing n bits of information.“Threshold voltage” herein shall refer to the voltage level that definesa boundary between two neighboring voltage distributions correspondingto two logical levels. Thus, the read operation can be performed bycomparing the measured voltage exhibited by the memory cell to one ormore reference voltage levels in order to distinguish between twological levels for single-level cells and between multiple logicallevels for multi-level cells.

Due to the phenomenon known as slow charge loss, the threshold voltageof a memory cell changes in time as the electric charge of the cell isdegrading, which is referred to as “temporal voltage shift” (since thedegrading electric charge causes the voltage distributions to shiftalong the voltage axis towards lower voltage levels). The thresholdvoltage is changing rapidly at first (immediately after the memory cellwas programmed), and then slows down in an approximately logarithmiclinear fashion with respect to the time elapsed since the cellprogramming event. Accordingly, failure to mitigate the temporal voltageshift caused by the slow charge loss can result in the increased biterror rate in read operations.

However, various common implementations either fail to adequatelyaddress the temporal voltage shift or employ inefficient strategiesresulting in high bit error rates and/or exhibiting other shortcomings.Embodiments of the present disclosure address the above-noted and otherdeficiencies by implementing a memory sub-system that employs blockfamily based error avoidance strategies, thus significantly improvingthe bit error rate exhibited by the memory sub-system.

In accordance with embodiments of the present disclosure, the temporalvoltage shift is selectively tracked for programmed blocks grouped byblock families, and appropriate voltage offsets, which are based onblock affiliation with a certain block family, are applied to the baseread levels in order to perform read operations. “Block family” hereinshall refer to a set of blocks that have been programmed within aspecified time window and a specified temperature window. Since the timeelapsed after programming and temperature are the main factors affectingthe temporal voltage shift, all blocks and/or partitions within a singleblock family are presumed to exhibit similar distributions of thresholdvoltages in memory cells, and thus would require the same voltageoffsets to be applied to the base read levels for read operations. “Baseread level” herein shall refer to the initial threshold voltage levelexhibited by the memory cell immediately after programming. In someimplementations, base read levels can be stored in the metadata of thememory device.

Block families can be created asynchronously with respect to blockprogramming events. In an illustrative example, a new block family canbe created whenever a specified period of time (e.g., a predeterminednumber of minutes) has elapsed since creation of the last block familyor the reference temperature of memory cells has changed by more than aspecified threshold value. The memory sub-system controller can maintainan identifier of the active block family, which is associated with oneor more blocks as they are being programmed.

The memory sub-system controller can periodically perform a calibrationprocess in order to associate each die of every block family with one ofthe predefined threshold voltage offset bins, which is in turnassociated with the voltage offset to be applied for read operations.The associations of blocks with block families and block families anddies with threshold voltage offset bins can be stored in respectivemetadata tables maintained by the memory sub-system controller.

Upon receiving a read command, the memory sub-system controller canidentify the block family associated with the block identified by thelogical block address (LBA) specified by the read command, identify thethreshold voltage offset bin associated with the block family and die onwhich the block resides, compute the new threshold voltage by additivelyapplying the threshold voltage offset associated with the thresholdvoltage offset bin to the base read level, and perform the readoperation using the new threshold voltage, as described in more detailherein below.

Therefore, advantages of the systems and methods implemented inaccordance with some embodiments of the present disclosure include, butare not limited to, improving the bit error rate in read operations bymaintaining metadata tracking groups of blocks (block families) that arepresumed to exhibit similar voltage distributions and selectivelyperforming calibration operations for limited subsets of blocks based ontheir block family association, as described in more detail hereinbelow.

FIG. 1 illustrates an example computing system 100 that includes amemory sub-system 110 in accordance with some embodiments of the presentdisclosure. The memory sub-system 110 can include media, such as one ormore volatile memory devices (e.g., memory device 140), one or morenon-volatile memory devices (e.g., memory device 130), or a combinationof such.

A memory sub-system 110 can be a storage device, a memory module, or ahybrid of a storage device and memory module. Examples of a storagedevice include a solid-state drive (SSD), a flash drive, a universalserial bus (USB) flash drive, an embedded Multi-Media Controller (eMMC)drive, a Universal Flash Storage (UFS) drive, a secure digital (SD)card, and a hard disk drive (HDD). Examples of memory modules include adual in-line memory module (DIMM), a small outline DIMM (SO-DIMM), andvarious types of non-volatile dual in-line memory module (NVDIMM).

The computing system 100 can be a computing device such as a desktopcomputer, laptop computer, network server, mobile device, a vehicle(e.g., airplane, drone, train, automobile, or other conveyance),Internet of Things (IoT) enabled device, embedded computer (e.g., oneincluded in a vehicle, industrial equipment, or a networked commercialdevice), or such computing device that includes memory and a processingdevice (e.g., a processor).

The computing system 100 can include a host system 120 that is coupledto one or more memory sub-systems 110. In some embodiments, the hostsystem 120 is coupled to different types of memory sub-systems 110. FIG.1 illustrates one example of a host system 120 coupled to one memorysub-system 110. As used herein, “coupled to” or “coupled with” generallyrefers to a connection between components, which can be an indirectcommunicative connection or direct communicative connection (e.g.,without intervening components), whether wired or wireless, includingconnections such as electrical, optical, magnetic, etc.

The host system 120 can include a processor chipset and a software stackexecuted by the processor chipset. The processor chipset can include oneor more cores, one or more caches, a memory controller (e.g., NVDIMMcontroller), and a storage protocol controller (e.g., PCIe controller,SATA controller). The host system 120 uses the memory sub-system 110,for example, to write data to the memory sub-system 110 and read datafrom the memory sub-system 110.

The host system 120 can be coupled to the memory sub-system 110 via aphysical host interface. Examples of a physical host interface include,but are not limited to, a serial advanced technology attachment (SATA)interface, a peripheral component interconnect express (PCIe) interface,universal serial bus (USB) interface, Fibre Channel, Serial AttachedSCSI (SAS), a double data rate (DDR) memory bus, Small Computer SystemInterface (SCSI), a dual in-line memory module (DIMM) interface (e.g.,DIMM socket interface that supports Double Data Rate (DDR)), Open NANDFlash Interface (ONFI), Double Data Rate (DDR), Low Power Double DataRate (LPDDR), etc. The physical host interface can be used to transmitdata between the host system 120 and the memory sub-system 110. The hostsystem 120 can further utilize an NVM Express (NVMe) interface to accesscomponents (e.g., memory devices 130) when the memory sub-system 110 iscoupled with the host system 120 by the PCIe interface. The physicalhost interface can provide an interface for passing control, address,data, and other signals between the memory sub-system 110 and the hostsystem 120. FIG. 1 illustrates a memory sub-system 110 as an example. Ingeneral, the host system 120 can access multiple memory sub-systems viaa same communication connection, multiple separate communicationconnections, and/or a combination of communication connections.

The memory devices 130,140 can include any combination of the differenttypes of non-volatile memory devices and/or volatile memory devices. Thevolatile memory devices (e.g., memory device 140) can be, but are notlimited to, random access memory (RAM), such as dynamic random accessmemory (DRAM) and synchronous dynamic random access memory (SDRAM).

Some examples of non-volatile memory devices (e.g., memory device 130)include negative-and (NAND) type flash memory and write-in-place memory,such as a three-dimensional cross-point (“3D cross-point”) memorydevice, which is a cross-point array of non-volatile memory cells. Across-point array of non-volatile memory can perform bit storage basedon a change of bulk resistance, in conjunction with a stackablecross-gridded data access array. Additionally, in contrast to manyflash-based memories, cross-point non-volatile memory can perform awrite in-place operation, where a non-volatile memory cell can beprogrammed without the non-volatile memory cell being previously erased.NAND type flash memory includes, for example, two-dimensional NAND (2DNAND) and three-dimensional NAND (3D NAND).

Each of the memory devices 130 can include one or more arrays of memorycells. One type of memory cell, for example, single level cells (SLC)can store one bit per cell. Other types of memory cells, such asmulti-level cells (MLCs), triple level cells (TLCs), and quad-levelcells (QLCs), can store multiple bits per cell. In some embodiments,each of the memory devices 130 can include one or more arrays of memorycells such as SLCs, MLCs, TLCs, QLCs, or any combination of such. Insome embodiments, a particular memory device can include an SLC portion,and an MLC portion, a TLC portion, or a QLC portion of memory cells. Thememory cells of the memory devices 130 can be grouped as pages that canrefer to a logical unit of the memory device used to store data. Withsome types of memory (e.g., NAND), pages can be grouped to form blocks.

Although non-volatile memory devices such as 3D cross-point array ofnon-volatile memory cells and NAND type memory (e.g., 2D NAND, 3D NAND)are described, the memory device 130 can be based on any other type ofnon-volatile memory, such as read-only memory (ROM), phase change memory(PCM), self-selecting memory, other chalcogenide based memories,ferroelectric transistor random-access memory (FeTRAM), ferroelectricrandom access memory (FeRAM), magneto random access memory (MRAM), SpinTransfer Torque (STT)-MRAM, conductive bridging RAM (CBRAM), resistiverandom access memory (RRAM), oxide based RRAM (OxRAM), negative-or (NOR)flash memory, and electrically erasable programmable read-only memory(EEPROM).

A memory sub-system controller 115 (or controller 115 for simplicity)can communicate with the memory devices 130 to perform operations suchas reading data, writing data, or erasing data at the memory devices 130and other such operations. The memory sub-system controller 115 caninclude hardware such as one or more integrated circuits and/or discretecomponents, a buffer memory, or a combination thereof. The hardware caninclude digital circuitry with dedicated (i.e., hard-coded) logic toperform the operations described herein. The memory sub-systemcontroller 115 can be a microcontroller, special purpose logic circuitry(e.g., a field programmable gate array (FPGA), an application specificintegrated circuit (ASIC), etc.), or other suitable processor.

The memory sub-system controller 115 can include a processor 117 (e.g.,processing device) configured to execute instructions stored in a localmemory 119. In the illustrated example, the local memory 119 of thememory sub-system controller 115 includes an embedded memory configuredto store instructions for performing various processes, operations,logic flows, and routines that control operation of the memorysub-system 110, including handling communications between the memorysub-system 110 and the host system 120.

In some embodiments, the local memory 119 can include memory registersstoring memory pointers, fetched data, etc. The local memory 119 canalso include read-only memory (ROM) for storing micro-code. While theexample memory sub-system 110 in FIG. 1 has been illustrated asincluding the controller 115, in another embodiment of the presentdisclosure, a memory sub-system 110 does not include a controller 115,and can instead rely upon external control (e.g., provided by anexternal host, or by a processor or controller separate from the memorysub-system).

In general, the memory sub-system controller 115 can receive commands oroperations from the host system 120 and can convert the commands oroperations into instructions or appropriate commands to achieve thedesired access to the memory devices 130. The memory sub-systemcontroller 115 can be responsible for other operations such as wearleveling operations, garbage collection operations, error detection anderror-correcting code (ECC) operations, encryption operations, cachingoperations, and address translations between a logical address (e.g.,logical block address (LBA), namespace) and a physical address (e.g.,physical block address) that are associated with the memory devices 130.The memory sub-system controller 115 can further include host interfacecircuitry to communicate with the host system 120 via the physical hostinterface. The host interface circuitry can convert the commandsreceived from the host system into command instructions to access thememory devices 130 as well as convert responses associated with thememory devices 130 into information for the host system 120.

In some implementations, memory sub-system 110 can use a stripingscheme, according to which every the data payload (e.g., user data)utilizes multiple dies of the memory devices 130 (e.g., NAND type flashmemory devices), such that the payload is distributed through a subsetof dies, while the remaining one or more dies are used to store theerror correction information (e.g., parity bits). Accordingly, a set ofblocks distributed across a set of dies of a memory device using astriping scheme is referred herein to as a “superblock.”

The memory sub-system 110 can also include additional circuitry orcomponents that are not illustrated. In some embodiments, the memorysub-system 110 can include a cache or buffer (e.g., DRAM) and addresscircuitry (e.g., a row decoder and a column decoder) that can receive anaddress from the controller 115 and decode the address to access thememory devices 130.

In some embodiments, the memory devices 130 include local mediacontrollers 135 that operate in conjunction with memory sub-systemcontroller 115 to execute operations on one or more memory cells of thememory devices 130. An external controller (e.g., memory sub-systemcontroller 115) can externally manage the memory device 130 (e.g.,perform media management operations on the memory device 130). In someembodiments, a memory device 130 is a managed memory device, which is araw memory device combined with a local controller (e.g., localcontroller 135) for media management within the same memory devicepackage. An example of a managed memory device is a managed NAND (MNAND)device.

The memory sub-system 110 includes a block family manager component 113that can be used to implement the block family-based error avoidancestrategies in accordance with embodiments of the present disclosure. Insome embodiments, the controller 115 includes at least a portion of theblock family manager component 113. For example, the controller 115 caninclude a processor 117 (processing device) configured to executeinstructions stored in local memory 119 for performing the operationsdescribed herein. In some embodiments, the block family managercomponent 113 is part of the host system 120, an application, or anoperating system. The block family manager component 113 can manageblock families associated with the memory devices 130, as described inmore detail herein below.

FIG. 2 schematically illustrates the temporal voltage shift caused bythe slow charge loss exhibited by triple-level memory cells. While theillustrative example of FIG. 2 utilizes triple-level cells, the sameobservations can be made and, accordingly, the same remedial measuresare applicable to single level cells and multi-level cells in order tocompensate for the slow charge loss.

As noted herein above, a memory cell can be programmed (written to) byapplying a certain voltage to the memory cell, which results in anelectric charge being held by the memory cell, thus allowing modulationof the voltage distributions produced by the memory cell. Preciselycontrolling the amount of the electric charge stored by the memory cellallows to establish multiple threshold voltage levels corresponding todifferent logical levels, thus effectively allowing a single memory cellto store multiple bits of information: a memory cell operated with 2ndifferent threshold voltage levels is capable of storing n bits ofinformation.

In FIG. 2, each graph 220A-220N shows a voltage distribution produced bymemory cells programmed by a respective write level (which can beassumed to be at the midpoint of the distribution) to encode acorresponding logical level (“000” through “111” in case of a TLC). Inorder to distinguish between neighboring distributions (corresponding totwo different logical levels), the threshold voltage levels (shown bydashed vertical lines) are defined, such that any measured voltage thatfalls below a threshold level is associated with one distribution of thepair of neighboring distributions, while any measured voltage that isgreater than or equal to the threshold level is associated with anotherdistribution of the pair of neighboring distributions.

As seen from comparing example charts 210 and 230, which reflect thetime periods immediately after programming and 440 hours afterprogramming, respectively, the voltage distributions change in time dueto the slow charge loss, which results in drifting values of thethreshold voltage levels, which are shown by dashed vertical lines. Invarious embodiments of the present disclosure, the temporal voltageshift is selectively tracked for programmed blocks grouped by blockfamilies, and appropriate voltage offsets, which are based on blockaffiliation with a certain block family, are applied to the base readlevels in order to perform read operations.

FIG. 3 depicts an example graph 300 illustrating the dependency of thethreshold voltage offset 310 on the time after program 320 (i.e., theperiod of time elapsed since the block had been programmed. Asschematically illustrated by FIG. 3, blocks of the memory device aregrouped into block families 330A-330N, such that each block familyincludes one or more blocks that have been programmed within a specifiedtime window and a specified temperature window. As noted herein above,since the time elapsed after programming and temperature are the mainfactors affecting the temporal voltage shift, all blocks and/orpartitions within a single block family 310 are presumed to exhibitsimilar distributions of threshold voltages in memory cells, and thuswould require the same voltage offsets for read operations.

Block families can be created asynchronously with respect to blockprogramming events. In an illustrative example, the memory sub-systemcontroller 115 of FIG. 1 can create a new block family whenever aspecified period of time (e.g., a predetermined number of minutes) haselapsed since creation of the last block family or whenever thereference temperature of memory cells, which is updated at specifiedtime intervals, has changed by more than a specified threshold valuesince creation of the current block family.

A newly created block family can be associated with bin 0. Then, thememory sub-system controller can periodically perform a calibrationprocess in order to associate each die of every block family with one ofthe predefines threshold voltage offset bins (bins 0-7 in theillustrative example of FIG. 3), which is in turn associated with thevoltage offset to be applied for read operations. The associations ofblocks with block families and block families and dies with thresholdvoltage offset bins can be stored in respective metadata tablesmaintained by the memory sub-system controller.

FIG. 4 schematically illustrates a set of predefined threshold voltageoffset bins (bin 0 to bin 9), in accordance with embodiments of thepresent disclosure. As schematically illustrated by FIG. 4, thethreshold voltage offset graph can be subdivided into multiple thresholdvoltage offset bins, such that each bin corresponds to a predeterminedrange of threshold voltage offsets. While the illustrative example ofFIG. 4 defines ten bins, in other implementations, various other numbersof bins can be employed (e.g., 64 bins). Based on a periodicallyperformed calibration process, the memory sub-system controllerassociates each die of every block family with a threshold voltageoffset bin, which defines a set of threshold voltage offsets to beapplied to the base voltage read level in order to perform readoperations, as described in more detail herein below.

FIG. 5 schematically illustrates block family management operationsimplemented by the block family manager component of thememory-sub-system controller operating in accordance with embodiments ofthe present disclosure. As schematically illustrated by FIG. 5, theblock family manager 510 can maintain, in a memory variable, anidentifier 520 of the active block family, which is associated with oneor more blocks of cursors 530A-530K as they are being programmed.“Cursor” herein shall broadly refer to a location on the memory deviceto which the data is being written.

The memory sub-system controller can utilize a power on minutes (POM)clock for tracking the creation times of block families. In someimplementations, a less accurate clock, which continues running when thecontroller is in various low-power states, can be utilized in additionto the POM clock, such that the POM clock is updated based on the lessaccurate clock upon the controller wake-up from the low-power state.

Thus, upon initialization of each block family, the current time 540 isstored in a memory variable as the block family start time 550. As theblocks are programmed, the current time 540 is compared to the blockfamily start time 550. Responsive to detecting that the difference ofthe current time 540 and the block family start time 550 is greater thanor equal to the specified time period (e.g., a predetermined number ofminutes), the memory variable storing the active block family identifier520 is updated to store the next block family number (e.g., the nextsequential integer number), and the memory variable storing the blockfamily start time 550 is updated to store the current time 540.

The block family manager 510 can also maintain two memory variables forstoring the high and low reference temperatures of a selected die ofeach memory device. Upon initialization of each block family, the hightemperature 560 and the low temperature 570 variable store the value ofthe current temperature of the selected die of the memory device. Inoperation, while the active block family identifier 520 remains thesame, temperature measurements are periodically obtained and comparedwith the stored high temperature 560 and the low temperature 570 values,which are updated accordingly: should the temperature measurement befound to be greater than or equal to the value stored by the hightemperature variable 560, the latter is updated to store thattemperature measurement; conversely, should the temperature measurementbe found to fall below the value stored by the low temperature variable570, the latter is updated to store that temperature measurement.

The block family manager 510 can further periodically compute thedifference between the high temperature 560 and the low temperature 570.Responsive to determining that the difference between the hightemperature 560 and the low temperature 570 is greater than or equal toa specified temperature threshold, the block family manager 510 cancreate a new active block family: the memory variable storing the activeblock family identifier 520 is updated to store the next block familynumber (e.g., the next sequential integer number), the memory variablestoring the block family start time 550 is updated to store the currenttime 540, and the high temperature 560 and the low temperature 570variables are updated to store the value of the current temperature ofthe selected die of the memory device.

At the time of programming a block, the memory sub-system controllerassociates the block with the currently active block family. Theassociation of each block with a corresponding block family is reflectedby the block family metadata 580, as described in more detail hereinbelow with reference to FIG. 7.

As noted herein above, based on a periodically performed calibrationprocess, the memory sub-system controller associates each die of everyblock family with a threshold voltage offset bin, which defines a set ofthreshold voltage offsets to be applied to the base voltage read levelin order to perform read operations. The calibration process involvesperforming, with respect to a specified number of randomly selectedblocks within the block family that is being calibrated, read operationsutilizing different threshold voltage offsets, and choosing thethreshold voltage offset that minimizes the error rate of the readoperation.

FIG. 6 schematically illustrates selecting block families forcalibration, in accordance with embodiments of the present disclosure.As schematically illustrated by FIG. 6, the memory sub-system controllercan limit the calibration operations to the oldest block family in eachbin (e.g., block family 610 in bin 0 and block family 620 in bin 1),since it is the oldest block family that will, due to the slow chargeloss, migrate to the next bin before any other block family of thecurrent bin.

FIG. 7 schematically illustrates example metadata maintained by thememory sub-system controller for associating blocks and/or partitionswith block families, in accordance with embodiments of the presentdisclosure. As schematically illustrated by FIG. 7, the memorysub-system controller can maintain the superblock table 710, the familytable 720, and the offset table 730.

Each record of the superblock table 710 specifies the block familyassociated with the specified superblock and partition combination. Insome implementations, the superblock table records can further includetime and temperature values associated with the specified superblock andpartition combination.

The family table 720 is indexed by the block family number, such thateach record of the family table 720 specifies, for the block familyreferenced by the index of the record, a set of threshold voltage offsetbins associated with respective dies of the block family. In otherwords, each record of the family table 720 includes a vector, eachelement of which specifies the threshold voltage offset bin associatedwith the die referenced by the index of the vector element. Thethreshold voltage offset bins to be associated with the block familydies can be determined by the calibration process, as described in moredetail herein above.

Finally, the offset table 730 is indexed by the bin number. Each recordof the offset table 730 specifies a set of threshold voltage offsets(e.g., for TLC, MLC, and/or SLC) associated with threshold voltageoffset bin.

The metadata tables 710-730 can be stored on one or more memory devices130 of FIG. 1. In some implementations, at least part of the metadatatables can be cached in the local memory 119 of the memory sub-systemcontroller 115 of FIG. 1.

In operation, upon receiving a read command, the memory sub-systemcontroller determines the physical address corresponding to the logicalblock address (LBA) specified by the read command. Components of thephysical address, such as the physical block number and the dieidentifier, are utilized for performing the metadata table walk: first,the superblock table 710 is used to identify the block family identifiercorresponding to the physical block number; then, the block familyidentifier is used as the index to the family table 720 in order todetermine the threshold voltage offset bin associated with the blockfamily and the die; finally, the identified threshold voltage offset binis used as the index to the offset table 730 in order to determine thethreshold voltage offset corresponding to the bin. The memory sub-systemcontroller can then additively apply the identified threshold voltageoffset to the base voltage read level in order to perform the requestedread operation.

In the illustrative example of FIG. 7, the superblock table 710 mapspartition 0 of the superblock 0 to block family 4, which is utilized asthe index to the family table 720 in order to determine that die 0 ismapped to bin 3. The latter value is used as the index to the offsettable in order to determine the threshold voltage offset values for bin3.

FIG. 8 is a flow diagram of an example method 800 of block familymanagement implemented by a memory sub-system controller operating inaccordance with some embodiments of the present disclosure. The method800 can be performed by processing logic that can include hardware(e.g., processing device, circuitry, dedicated logic, programmablelogic, microcode, hardware of a device, integrated circuit, etc.),software (e.g., instructions run or executed on a processing device), ora combination thereof. In some embodiments, the method 800 is performedby the block family manager component 113 of FIG. 1. Although shown in aparticular sequence or order, unless otherwise specified, the order ofthe operations can be modified. Thus, the illustrated embodiments shouldbe understood only as examples, and the illustrated operations can beperformed in a different order, while some operations can be performedin parallel. Additionally, one or more operations can be omitted in someembodiments. Thus, not all illustrated operations are required in everyembodiment, and other process flows are possible.

At operation 810, the processing device of the memory sub-systemcontroller initializes a block family and stores, in a memory variable,an identifier of the block family.

At operation 815, the processing device initializes a timer associatedwith the block family.

At operation 820, the processing device initializes the low temperatureand the high temperature associated with the block family to store thecurrent temperature of a selected die of the memory device (e.g., arandomly selected die).

Responsive to determining, at operation 825, that the difference betweenthe high temperature and the low temperature values is greater than orequal to a specified temperature threshold value, the method branches tooperation 835; otherwise, the processing continues at operation 830.

Responsive to determining, at operation 830, that the value of the timerassociated with the block family is greater than or equal to a specifiedtimeout value, the processing device may, at operation 835, close theblock family; otherwise, the method loops back to operation 825.

Responsive to performing operation 835, the method loops back tooperation 810.

Operations 850-870 are performed asynchronously with respect tooperations 810-860. In an illustrative example, operations 810-835 areperformed by a first processing thread, and operations 850-870 areperformed by a second processing thread.

At operation 850, the processing device receives a temperaturemeasurement at the selected die of the memory device.

Responsive to determining, at operation 855, that the receivedtemperature measurement is greater than or equal to the stored hightemperature value, the processing device, at operation 860, updates thehigh temperature value to store the received temperature measurement.

Responsive to determining, at operation 865, that the receivedtemperature measurement falls below the stored low temperature value,the processing device, at operation 870, updates the low temperaturevalue to store the received temperature measurement.

FIG. 9 is a flow diagram of an example method of performing a readoperation by a memory sub-system controller operating in accordance withsome embodiments of the present disclosure. The method 900 can beperformed by processing logic that can include hardware (e.g.,processing device, circuitry, dedicated logic, programmable logic,microcode, hardware of a device, integrated circuit, etc.), software(e.g., instructions run or executed on a processing device), or acombination thereof. In some embodiments, the method 900 is performed bythe block family manager component 113 of FIG. 1. Although shown in aparticular sequence or order, unless otherwise specified, the order ofthe operations can be modified. Thus, the illustrated embodiments shouldbe understood only as examples, and the illustrated operations can beperformed in a different order, while some operations can be performedin parallel. Additionally, one or more operations can be omitted in someembodiments. Thus, not all illustrated operations are required in everyembodiment, and other process flows are possible.

At operation 910, the processing device of the memory sub-systemcontroller receives a read command specifying an identifier of a logicalblock.

At operation 920, the processing device translates the identifier of thelogical block into a physical address (PA) of a physical block stored onthe memory device. In an illustrative example, the translation isperformed by looking up the logical block identifier (also referred toas logical block address, or LBA) in a logical-to-physical (L2P) tableassociated with the memory device. The L2P table includes multiplemapping records, such that each mapping record maps an LBA to acorresponding physical address. For flash memory devices, the physicaladdress can include channel identifier, die identifier, page identifier,plane identifier and/or frame identifier.

At operation 930, the processing device identifies, based on blockfamily metadata associated with the memory device, a block familyassociated with the physical address. In an illustrative example, theprocessing device utilizes the superblock table 710 of FIG. 7 in orderto identify the block family associated with the physical address.

At operation 940, the processing device determines a threshold voltageoffset associated with the block family and the memory device die. In anillustrative example, the processing device utilizes the block familytable 720 of FIG. 7, in order to determine the bin identifiercorresponding to the combination of the block family identifier and thedie identifier. The processing device then utilizes the offset table 730of FIG. 7 in order to determine the threshold voltage offsets for theidentified threshold voltage offset bin.

At operation 950, the processing device computes a modified thresholdvoltage by applying the identified threshold voltage offset to a baseread level voltage associated with the memory device. As noted hereinabove, the base read level voltage can be stored in the metadata area ofthe memory device.

At operation 960, the processing device utilizes the computed modifiedthreshold voltage in order to perform the requested read operation.Responsive to completing operation 960, the method terminates.

FIG. 10 illustrates an example machine of a computer system 1000 withinwhich a set of instructions, for causing the machine to perform any oneor more of the methodologies discussed herein, can be executed. In someembodiments, the computer system 1000 can correspond to a host system(e.g., the host system 120 of FIG. 1) that includes, is coupled to, orutilizes a memory sub-system (e.g., the memory sub-system 110 of FIG. 1)or can be used to perform the operations of a controller (e.g., toexecute an operating system to perform operations corresponding to theblock family manager component 113 of FIG. 1). In alternativeembodiments, the machine can be connected (e.g., networked) to othermachines in a LAN, an intranet, an extranet, and/or the Internet. Themachine can operate in the capacity of a server or a client machine inclient-server network environment, as a peer machine in a peer-to-peer(or distributed) network environment, or as a server or a client machinein a cloud computing infrastructure or environment.

The machine can be a personal computer (PC), a tablet PC, a set-top box(STB), a Personal Digital Assistant (PDA), a cellular telephone, a webappliance, a server, a network router, a switch or bridge, or anymachine capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by that machine. Further,while a single machine is illustrated, the term “machine” shall also betaken to include any collection of machines that individually or jointlyexecute a set (or multiple sets) of instructions to perform any one ormore of the methodologies discussed herein.

The example computer system 1000 includes a processing device 1002, amain memory 1004 (e.g., read-only memory (ROM), flash memory, dynamicrandom access memory (DRAM) such as synchronous DRAM (SDRAM) or RambusDRAM (RDRAM), etc.), a static memory 1010 (e.g., flash memory, staticrandom access memory (SRAM), etc.), and a data storage system 1018,which communicate with each other via a bus 1030.

Processing device 1002 represents one or more general-purpose processingdevices such as a microprocessor, a central processing unit, or thelike. More particularly, the processing device can be a complexinstruction set computing (CISC) microprocessor, reduced instruction setcomputing (RISC) microprocessor, very long instruction word (VLIW)microprocessor, or a processor implementing other instruction sets, orprocessors implementing a combination of instruction sets. Processingdevice 1002 can also be one or more special-purpose processing devicessuch as an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA), a digital signal processor (DSP),network processor, or the like. The processing device 1002 is configuredto execute instructions 1028 for performing the operations and stepsdiscussed herein. The computer system 1000 can further include a networkinterface device 1012 to communicate over the network 1020.

The data storage system 1018 can include a machine-readable storagemedium 1024 (also known as a computer-readable medium) on which isstored one or more sets of instructions 1028 or software embodying anyone or more of the methodologies or functions described herein. Theinstructions 1028 can also reside, completely or at least partially,within the main memory 1004 and/or within the processing device 1002during execution thereof by the computer system 1000, the main memory1004 and the processing device 1002 also constituting machine-readablestorage media. The machine-readable storage medium 1024, data storagesystem 1018, and/or main memory 1004 can correspond to the memorysub-system 110 of FIG. 1.

In one embodiment, the instructions 1028 include instructions toimplement functionality corresponding to the block family managercomponent 113 of FIG. 1. While the machine-readable storage medium 1024is shown in an example embodiment to be a single medium, the term“machine-readable storage medium” should be taken to include a singlemedium or multiple media that store the one or more sets ofinstructions. The term “machine-readable storage medium” shall also betaken to include any medium that is capable of storing or encoding a setof instructions for execution by the machine and that cause the machineto perform any one or more of the methodologies of the presentdisclosure. The term “machine-readable storage medium” shall accordinglybe taken to include, but not be limited to, solid-state memories,optical media, and magnetic media.

Some portions of the preceding detailed descriptions have been presentedin terms of algorithms and symbolic representations of operations ondata bits within a computer memory. These algorithmic descriptions andrepresentations are the ways used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self-consistent sequence of operations leading to adesired result. The operations are those requiring physicalmanipulations of physical quantities. Usually, though not necessarily,these quantities take the form of electrical or magnetic signals capableof being stored, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. The presentdisclosure can refer to the action and processes of a computer system,or similar electronic computing device, that manipulates and transformsdata represented as physical (electronic) quantities within the computersystem's registers and memories into other data similarly represented asphysical quantities within the computer system memories or registers orother such information storage systems.

The present disclosure also relates to an apparatus for performing theoperations herein. This apparatus can be specially constructed for theintended purposes, or it can include a general purpose computerselectively activated or reconfigured by a computer program stored inthe computer. Such a computer program can be stored in a computerreadable storage medium, such as, but not limited to, any type of diskincluding floppy disks, optical disks, CD-ROMs, and magnetic-opticaldisks, read-only memories (ROMs), random access memories (RAMs), EPROMs,EEPROMs, magnetic or optical cards, or any type of media suitable forstoring electronic instructions, each coupled to a computer system bus.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various general purposesystems can be used with programs in accordance with the teachingsherein, or it can prove convenient to construct a more specializedapparatus to perform the method. The structure for a variety of thesesystems will appear as set forth in the description below. In addition,the present disclosure is not described with reference to any particularprogramming language. It will be appreciated that a variety ofprogramming languages can be used to implement the teachings of thedisclosure as described herein.

The present disclosure can be provided as a computer program product, orsoftware, that can include a machine-readable medium having storedthereon instructions, which can be used to program a computer system (orother electronic devices) to perform a process according to the presentdisclosure. A machine-readable medium includes any mechanism for storinginformation in a form readable by a machine (e.g., a computer). In someembodiments, a machine-readable (e.g., computer-readable) mediumincludes a machine (e.g., a computer) readable storage medium such as aread only memory (“ROM”), random access memory (“RAM”), magnetic diskstorage media, optical storage media, flash memory devices, etc.

In the foregoing specification, embodiments of the disclosure have beendescribed with reference to specific example embodiments thereof. Itwill be evident that various modifications can be made thereto withoutdeparting from the broader spirit and scope of embodiments of thedisclosure as set forth in the following claims. The specification anddrawings are, accordingly, to be regarded in an illustrative senserather than a restrictive sense.

What is claimed is:
 1. A system comprising: a memory device; and aprocessing device, operatively coupled to the memory device, theprocessing device to: initialize a block family associated with a memorydevice; initialize a timeout associated with the block family;responsive to programming a block residing on the memory device,associate the block with the block family; and responsive to detectingexpiration of the timeout, close the block family.
 2. The system ofclaim 1, wherein associating the block with the block family furthercomprises: appending, to block family metadata, a record associating theblock with the block family.
 3. The system of claim 1, wherein theprocessing device is further to: initialize a low temperature and a hightemperature using a reference temperature at the memory device;responsive to determining that a difference between the high temperatureand the low temperature is greater than or equal to a specifiedthreshold temperature value, close the block family.
 4. The system ofclaim 3, wherein the processing device is further to: receive a secondreference temperature of the block family; responsive to determiningthat the second reference temperature is greater than or equal to thehigh temperature, update the high temperature to store the secondreference temperature; and responsive to determining that the secondreference temperature falls below the low temperature, update the lowtemperature to store the second reference temperature.
 5. The system ofclaim 1, wherein the processing device is further to: responsive toclosing the block family, initialize a new block family.
 6. The systemof claim 1, wherein the processing device is further to: responsive tocreating the block family, associate the block family with a firstthreshold voltage offset bin.
 7. The system of claim 6, wherein theprocessing device is further to: responsive to detecting a triggeringevent, associate the block family with a second threshold voltage offsetbin by calibrating an oldest block family associated with the firstthreshold voltage offset bin.
 8. The system of claim 1, wherein theprocessing device is further to: determine a threshold voltage offsetassociated with the block family; and compute a modified thresholdvoltage by applying the threshold voltage offset to a base read levelvoltage associated with the memory device; read, using the modifiedthreshold voltage, data from a block of the block family.
 9. A method,comprising: receiving, by a processing device, a read command specifyingan identifier of a logical block; translating the identifier of thelogical block into a physical address of a physical block stored on amemory device, wherein the physical address comprises an identifier of amemory device die; identifying, based on block family metadataassociated with the memory device, a block family associated with thephysical address; determining a threshold voltage offset associated withthe block family and the memory device die; computing a modifiedthreshold voltage by applying the threshold voltage offset to a baseread level voltage associated with the memory device die; and reading,using the modified threshold voltage, data from the physical block. 10.The method of claim 9, wherein the block family comprises a plurality ofblocks that have been programmed within at least one of: a specifiedtime window or a specified temperature window.
 11. The method of claim9, wherein the block family metadata comprises a first table including aplurality of records, wherein a record of the plurality of recordsassociates the physical block with the block family.
 12. The method ofclaim 9, wherein the block family metadata comprises a second tableincluding a plurality of records, wherein a record of the plurality ofrecords associates a plurality of dies of the block family withrespective threshold voltage offset bins.
 13. The method of claim 9,wherein the block family metadata comprises a third table including aplurality of records, wherein a record of the plurality of recordsassociates a threshold voltage offset bin with one or more thresholdvoltages to be applied to respective base voltage read levels forperforming read operations.
 14. A method, comprising: initializing, by aprocessing device, a block family associated with a memory device;initializing a timeout associated with the block family; initializing alow temperature and a high temperature using a reference temperature atthe memory device; responsive to programming a block residing on thememory device, associating the block with the block family; andresponsive to at least one of: detecting expiration of the timeout ordetermining that a difference between the high temperature and the lowtemperature is greater than or equal to a specified thresholdtemperature value, closing the block family.
 15. The method of claim 14,wherein associating the block with the block family further comprises:appending, to block family metadata, a record associating the block withthe block family.
 16. The method of claim 14, further comprising:receiving a second reference temperature of the block family; responsiveto determining that the second reference temperature is greater than orequal to the high temperature, updating the high temperature to storethe second reference temperature; and responsive to determining that thesecond reference temperature falls below the low temperature, updatingthe low temperature to store the second reference temperature.
 17. Themethod of claim 14, further comprising: responsive to closing the blockfamily, initializing a new block family.
 18. The method of claim 14,further comprising: responsive to creating the block family, associatingthe block family with a first threshold voltage offset bin.
 19. Themethod of claim 18, further comprising: associating the block familywith a second threshold voltage offset bin by calibrating an oldestblock family associated with the first threshold voltage offset bin. 20.The method of claim 14, wherein the processing device is further to:determine a threshold voltage offset associated with the block family;and compute a modified threshold voltage by applying the thresholdvoltage offset to a base read level voltage associated with the memorydevice; read, using the modified threshold voltage, data from a block ofthe block family.